System and method for protecting microelectromechanical systems array using back-plate with non-flat portion

Abstract

Disclosed is an electronic device utilizing interferometric modulation and a package of the device. The packaged device includes a substrate, an interferometric modulation display array formed on the substrate, and a back-plate. The back-plate is placed over the display array with a gap between the back-plate and the display array. The depth of the gap may vary across the back-plate. The back-plate can be curved or have a recess on its interior surface facing the display array. Thickness of the back-plate may vary. The device may include reinforcing structures which are integrated with the back-plate.

What is claimed is: 
     
       1. An electronic device, comprising:
 a substrate comprising a first surface and a second surface; 
 an array of microelectromechanical devices formed on the first surface of the substrate, wherein the microelectromechanical devices are configured to operate an optical processing with light incident to the second surface; 
 a back-plate placed over the array and having an interior surface and an exterior surface, the interior surface of the back-plate facing the array with a gap therebetween, the exterior surface facing away from the substrate, wherein the back-plate is configured so as not to transmit light involving the optical processing of the microelectromechanical devices; and 
 wherein the interior surface is substantially parallel to the second surface of the substrate, and wherein the exterior surface is curved. 
 
     
     
       2. The electronic device of  claim 1 , wherein the exterior surface of the back-plate is generally bowed away from the array. 
     
     
       3. The electronic device of  claim 1 , wherein a distance between the interior surface and the array varies across the array, and wherein the distance is measured from a point on the interior surface to a closest point of the array. 
     
     
       4. The electronic device of  claim 1 , wherein the exterior surface is substantially smoothly curved. 
     
     
       5. The electronic device of  claim 1 , wherein the interior surface comprises a central area and a peripheral area, and wherein the back-plate has a thickness defined between the interior and exterior surfaces that is generally greater in the central area than in the peripheral area. 
     
     
       6. The electronic device of  claim 1 , wherein the interior surface of the back-plate is substantially flat. 
     
     
       7. The electronic device of  claim 1 , wherein the back-plate comprises a protrusion extending toward the substrate along an edge of the back-plate. 
     
     
       8. The electronic device of  claim 1 , further comprising a seal located between the substrate and the interior surface along edges of the interior surface. 
     
     
       9. The electronic device of  claim 1 , wherein the exterior surface of the back-plate is curved substantially throughout. 
     
     
       10. The electronic device of  claim 1 , wherein the interior surface of the back-plate is flat substantially throughout. 
     
     
       11. An electronic device, comprising:
 a substrate comprising a first surface and a second surface; 
 an array of interferometric modulators formed on the first surface of the substrate, wherein the interferometric modulators are configured to operate an optical processing with light incident to the second surface; 
 means for covering the array, wherein said means comprises an interior surface and an exterior surface, the interior surface facing the array with a gap therebetween, the exterior surface facing away from the substrate, wherein the covering means is configured so as not to transmit light involving the optical processing of the interferometric modulators; and 
 wherein the interior surface of the covering means is substantially parallel to the second surface of the substrate, and wherein the exterior surface is curved. 
 
     
     
       12. The electronic device of  claim 11 , wherein the covering means comprises a curved back-plate. 
     
     
       13. The electronic device of  claim 11 , wherein the covering means has a recess formed on the interior surface thereof. 
     
     
       14. The electronic device of  claim 11 , wherein the covering means has varying thickness. 
     
     
       15. The electronic device of  claim 11 , wherein the interior surface of the back-plate is flat substantially throughout. 
     
     
       16. A method of making an electronic device, comprising:
 providing an intermediate device comprising a substrate, wherein the substrate comprises a first surface and a second surface, the intermediate device further comprising an array of microelectromechanical devices formed on the first surface of the substrate, wherein the microelectromechanical devices are configured to operate an optical processing with light incident to the second surface; and 
 forming a back-plate over the array of the intermediate device, the back-plate having an interior surface and an exterior surface, the interior surface facing the array with a gap therebetween, the exterior surface facing away from the substrate, wherein the back-plate is configured so as not to transmit light involving the optical processing of the microelectromechanical devices, wherein the interior surface is substantially parallel to the second surface of the substrate, and wherein the exterior surface is curved. 
 
     
     
       17. The method of  claim 16  wherein forming the back-plate further comprises:
 providing the back-plate having the interior surface; 
 placing the back-plate over the array such that the interior surface faces the array; and 
 binding the back-plate with the substrate along a periphery of the back-plate. 
 
     
     
       18. The method of  claim 17 , wherein the exterior surface is curved substantially throughout. 
     
     
       19. The method of  claim 17 , wherein the interior surface is substantially flat in a generally central area thereof. 
     
     
       20. The method of  claim 17 , wherein the back-plate has a varying thickness. 
     
     
       21. The method of  claim 17 , wherein the interior surface comprises a central area and a peripheral area, and wherein the back-plate has a thickness defined between the interior and exterior surfaces that is generally greater in the central area than in the peripheral area. 
     
     
       22. The method of  claim 17 , wherein the exterior surface of the back-plate is curved substantially throughout. 
     
     
       23. An electronic device produced by a method comprising:
 providing an intermediate device comprising a substrate, wherein the substrate comprises a first surface and a second surface, and wherein the intermediate device further comprises an array of microelectromechanical devices formed on the first surface of the substrate, wherein the microelectromechanical devices are configured to operate an optical processing with light incident to the second surface; and 
 forming a back-plate over the array of the intermediate device with a gap between the back-plate and the array, the back-plate having an interior surface facing the array and an exterior surface facing away from the array, wherein the back-plate is configured so as not to transmit light involving the optical processing of the microelectromechanical devices, and wherein the interior surface of the back-plate is substantially parallel to the second surface of the substrate, and wherein the exterior surface is curved. 
 
     
     
       24. The electronic device of  claim 22 , wherein the interior surface comprises a central area and a peripheral area, and wherein the back-plate comprises at least one recess in the central area. 
     
     
       25. The electronic device of  claim 22 , wherein the back-plate has a varying thickness. 
     
     
       26. The electronic device of  claim 22 , wherein the interior surface comprises a central area and a peripheral area, and wherein the back-plate has a thickness that is generally greater in the central area than in the peripheral area. 
     
     
       27. The electronic device of  claim 22 , wherein the interior surface of the back-plate is flat substantially throughout.